U.S. patent number 4,757,402 [Application Number 06/914,996] was granted by the patent office on 1988-07-12 for slider assembly for supporting a magnetic head.
This patent grant is currently assigned to Censtor Corp.. Invention is credited to Frank S. C. Mo.
United States Patent |
4,757,402 |
Mo |
July 12, 1988 |
Slider assembly for supporting a magnetic head
Abstract
A magnetic head assembly including a slider (15) for supporting
a magnetic transducer (12) adjacent the surface of a recording
media (14) on an air film, said slider including an air bearing
member (26) having a peripheral wall (38) extending toward said
media and presenting a substantially equal cross sectional area to
the air film moving with the media as the head is skewed slightly
relative to the oncoming air film.
Inventors: |
Mo; Frank S. C. (Cupertino,
CA) |
Assignee: |
Censtor Corp. (Santa Clara
County, CA)
|
Family
ID: |
25435058 |
Appl.
No.: |
06/914,996 |
Filed: |
October 3, 1986 |
Current U.S.
Class: |
360/235.4;
G9B/21.026; G9B/5.052; G9B/5.23 |
Current CPC
Class: |
G11B
5/1871 (20130101); G11B 5/6005 (20130101); G11B
21/21 (20130101) |
Current International
Class: |
G11B
5/187 (20060101); G11B 21/21 (20060101); G11B
5/60 (20060101); G11B 005/60 () |
Field of
Search: |
;360/103,102 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
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|
|
50133533 |
|
May 1977 |
|
JP |
|
53-29111 |
|
Mar 1978 |
|
JP |
|
Primary Examiner: Heinz; A. J.
Attorney, Agent or Firm: Moore; Gerald L.
Claims
I claim:
1. A magnetic head slider for supporting a magnetic transducer
adjacent the surface of a recording media on an air film flowing in
the general direction of relative motion between the magnetic head
and the media, said slider comprising:
a body member having a front and sides,
means to support the magnetic head on said body member,
air bearing means for maintaining said body member a predetermined
flying height from said media surface with relative motion between
said slider and media, comprising:
a plurality of air bearing members fixed to said body member and
having a configuration including a peripheral wall extending toward
the media and terminating at an air bearing surface formed with a
first portion extending generally parallel to said media surface to
create an air bearing for supporting the slider in spaced
relationship from said media surface, and
said air bearing member peripheral walls being shaped to present a
substantially equal cross sectional area to oncoming air film
approaching from directly in front of said slider or from the front
and side direction thereto to limit any change in lift due to
skewing of the slider relative to the air film flow direction.
2. A magnetic head slider for supporting a magnetic transducer
adjacent the surface of a recording media on an air film flowing in
the general direction of relative motion between the magnetic head
and the media, spaced from the surface of said slider
comprising:
a body member,
means to support the magnetic head on said body member, and
an air bearing means for creating a lift effect and maintaining
said body member at a predetermined flying height relative to said
media surface with relative motion between the media and body
member and as the body member is skewed relative to recording
media, comprising:
a plurality of air bearing members each having a configuration
including peripheral wall members extending from the body member
towards the media and terminating at an air bearing surface formed
with a first portion extending parallel to the media surface to
create an air bearing for supporting the slider in spaced
relationship relative to the media surface,
at least some of said air bearing members being positioned to
create a substantial lifting effect to maintain the slider at a
predetermined distance from and at a predetermined attitude
relative to the media surface, and
those air bearing members positioned to create a substantial lift
effect being formed to present no change of the cross sectional
area of the bearing members to the air film as the slider is skewed
relative thereto.
3. A magnetic head slider as defined in claim 2 wherein said air
bearing members are all cylindrical in configuration.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a slider assembly that exhibits improved
flying characteristics especially when the head is skewed as
frequently occurs with rotary actuators.
2. Description of the Prior Art
With state of the art data recording wherein a magnetic head is
flown over a disk on an air bearing assembly, the trend is to
position the head closer to the magnetic surface. Additionally,
when the disk is stopped sometimes the slider is allowed to come to
rest directly on the magnetic surface. Frequently such systems
utilize a rotary actuator for supporting the head; that is, the
head is supported on an arm which is pivoted about a point such
that the head is moved on an arc that approximates movement on a
radius of the recording disk.
The slider assembly is supported on the air film that moved with
the magnetic disk and forms an air bearing by the interaction of
this film of air and the underside of the slider. As the slider is
moved closer and closer to the disk, the possibility of contact is
increased. Additionally, with the at-rest contact between the
slider and the magnetic surface it is highly desired that the head
raise to the flying height out of contact with the disk as soon as
possible on start up and that the head remains flying as long as
possible above the disk surface on shutdown.
With the use of a rotary actuator the slider is not always directly
aligned with the directional flow of the air film. The air film
does not flow directly circumferentially with the disk but instead
always flows slightly outward due primarily to centrifugal forces.
With the slider being moved along an arc it is not always
positioned exactly perpendicular to the disk radius. These factors
tend to introduce the problems of skewing which occur when the
slider is not directly aligned with the direction of air flow. With
skewing of the head it is common for the lift forces to diminish
thereby lowering the flying height and increasing the possibilities
of contact with the disk surface. As pointed out before, state of
the art recording has required that the slider fly closer to the
disk thereby lessening the margin for error. Additionally, with the
recording of data at higher and higher densities, an unplanned
contact with the magnetic film can result in catastrophic losses if
damage to the magnetic film occurs. Thus, the lower flying height
has greatly diminished the margin for variances in the flying
height of the magnetic head in present day and future magnetic
recording systems.
It is the purpose of the present invention to provide an improved
slider assembly which provides for a quicker take off of the head
from the disk surface, maintains the slider assembly at a more
stable attitude for a better regulation of the head flying height,
and greatly lessens the effect of skewing on the flying height.
SUMMARY OF THE INVENTION
A magnetic head assembly including a slider for supporting a
magnetic transducer adjacent to a recording media on an air film,
wherein the head assembly includes a body member for supporting the
magnetic transducer, and an air bearing means comprising an air
bearing member having a peripheral wall terminating at an air
bearing surface positioned adjacent the media to form a lifting
force for supporting the slider and magnetic transducer above the
magnetic surface. The air bearing member is formed with a
peripheral wall configured such that the member presents a
substantially equal cross sectional area to the oncoming air film
even though the slider is skewed slightly relative to the oncoming
air thereby to maintain a substantially unchanged lifting force
allowing the head to fly at a steady height.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a top plan view showing a rotary actuator and magnetic
head assembly positioned over a portion of a magnetic recording
disk;
FIG. 2 shows a prior art slider and transducer assembly;
FIG. 3 shows a first embodiment of the invention;
FIGS. 4 through 6 show other embodiments of the invention;
FIGS. 7, 8, and 9 are various views of yet another embodiment of
the invention;
FIG. 10 shows the take-off characteristics for a magnetic head
assembly employing the subject invention; and
FIG. 11 shows the effect of changes in the skew angle of the
magnetic head assembly on the flying height.
DESCRIPTION OF THE INVENTION
In FIG. 1 shown a typical magnetic recording system including a
magnetic read/write head assembly 12 positioned above a rotating
disk 14 by an air bearing created by a slider assembly 15
positioned by an arm 16 fixed to an actuator 17 which pivots around
a pivot point 18. The disk is rotated in the direction of the arrow
19 and generally comprises a rigid or semi-rigid substrate (not
shown) covered by a magnetic material in which information can be
recorded in digital form by the alignment of magnetic particles in
selected areas.
A typical prior art slider and head assembly is shown in FIG. 2
comprising a slider body having air bearing members 26 extending
from one side. These members are spaced apart and form air bearing
surfaces 27. Thus, when the recording media 14 is rotated, a film
of air represented by the arrows 30 rotates therewith and interacts
with the air bearing surface to cause the head to be spaced at a
predetermined flying height above the surface for supporting the
read/write heads 31 a fixed distance from the magnetic film.
Forward inclined areas 32 assist in compressing the air film for
better support of the slider. Thus the slider functions in a very
efficient manner when the air film is approaching from headon,
i.e., the direction indicated from the arrow 34.
However, as indicated in FIG. 1, the head assembly is positioned by
an arm 16 that is fixed to an actuator 17 for rotation about a
pivot 18. Thus, when the slider is in the solid line position, the
air film indicated by the arrows 35 is approaching the slider
head-on, i.e., at a zero skew angle. However, when the slider is
moved near the inside of the recording member, i.e., in the dotted
line position, the air film, traveling in the direction of the
arrows 30, strikes the slider at an angle A to the optimum
direction. This action reduces the lifting force of the air bearing
and allows the head to settle somewhat closer to the media surface.
In the past such action has not been critical since the head
assembly was spaced further from the surface, however, with the
advent of the state of the art systems, the heads fly much closer
to the media, and any change can become critical.
In accordance with the present invention a slider and air bearing
member is provided that will have less change in flying height as
the approach or skew angle with the air film changes as described
previously. The overall concept of the air bearing member of this
embodiment is to present a cross sectional area to the oncoming air
film that changes less as the approach angle of the air film is
changed, thereby providing substantially the same lift to allow the
slider to fly at approximately an equal distance above the
recording media.
A first embodiment of the invention is shown in FIG. 3 in which the
slider body 24A is illustrated. This slider body includes an air
bearing member 35 formed in a cylindrical configuration to form a
circular air bearing surface 36 tapered slightly at the edge 37.
The air bearing member is formed with another peripheral wall 38.
The slider has attached thereto a magnetic transducer 39. Thus it
can be seen that with the air approaching in the direction of the
arrow 40 at a zero skew angle, an air bearing effect is realized at
the surface 36. Air approaching from this direction is exposed to
the side of a cylinder formed by the air bearing member. Similarly,
air approaching at a skew angle illustrated by the arrow 41 also is
exposed to the sidewall of a cylinder formed by the air bearing
member. Thus the effect is the same as far as the lift forces are
concerned because the air bearing member appears the same to the
oncoming air film approaching from either direction. As a result
there is little or no change in flying height due to skewing of the
head assembly except due to minor order cosine effects due to the
pitch angle of the slider.
In FIG. 4 is yet another embodiment of the invention comprising a
slider member 44 having formed on one surface a pair of air bearing
members 45 forming air bearing surfaces 46. In this instance a pair
of transducers 48 are fixed to the trailing edge of the head
assembly. Once again the oncoming film of air represented by the
arrow 50 will be encountered by a pair of circular air bearing
surfaces formed on the cylindrical air bearing members 45.
Similarly skewing of the head which will cause the air to approach,
for instance from the direction of the arrow 51, will also expose
the air film to a pair of circular air bearing surfaces thus
changing the lift exerted on the head assembly little if at
all.
FIGS. 5 and 6 also illustrate further embodiments of the invention
wherein slider assemblies 55 and 56, respectively, have positioned
thereon a plurality of air bearing members 57 all of cylindrical
configuration and forming air bearing surfaces 58 of substantially
equal area. Additionally transducers 59 are fixed to the trailing
edge of the slider member. In each of these embodiments a change in
the skew angle of the head assembly will change the exposure of the
air film to the air bearing surface very little due partly to the
cylindrical configuration of the air bearing members and also to
the fact that the air bearing members are separated by spaces
therebetween. Separation by these spaces allows the air film to
flow between the air bearing members and fuly load the air bearing
surfaces so as to create the necessary lift forces. Additionally a
change in the angle the film approaches each member still exposes
the air film to a air bearing member of similar cross section so as
not to change the lift forces generated by the air bearing
member.
Illustrated in FIGS. 7, 8, and 9 are still another embodiment of
the invention wherein a slider member 60 includes two rows of air
bearing members 61, 62, and 64. These air bearing members form
respectively, the air bearing surfaces 61A, 62A, and 64A.
Transducers 65 are fixed to the trailing edge of the slider. In
this instance, the air bearing members 61 and 62 are separated by a
laterally extending slot 67 while the forward bearing members 62
and 64 are separated by the transverse slot 68. It is recognized
that not all of the air bearing surfaces create equal lift in such
a structure and in this embodiment the surfaces 61A and 64A are
thought to create greater life forces. It is important that at
least those air bearing members creating the significant lift
forces incorporate the subject invention of presenting a
substantially equal cross-section even though the slider member
might become skewed. Thus at least the members 61 and 64 should
incorporate the present invention. For this reason they are
somewhat square in cross-section.
Turning now to FIG. 10 showing characteristics of the sliders 24
and 60 shown in FIGS. 2 and 7 respectively, it can be seen that the
take off characteristics of the assembly 24 illustrated by the
dotted line 70 are delayed considerably relatively to the take off
characteristics of the assembly 60 as illustrated by the solid line
71. This illustrates that with the cross slot separating the air
bearing members into distinct sections the head will lift from the
rotating media much sooner than with prior head assemblies
represented by the structure of FIG. 2. This results in less
contact between the head and disk with the attendant reduction in
wear to the disk surfaces and less accumulation of particles from
the magnetic coating on the head assembly.
FIG. 11 illustrates the effect of a change in the skew angle on the
flying height of the head. For the prior art head illustrated in
FIG. 2 changes in the flying height are illustrated by the dash
line 75 showing that the flying height changes considerably as the
skew angle increases. For the same changes in the skew angle on the
segmented air bearing member shown in FIG. 4 the solid line 76
illustrates that the flying height does not vary more than
approximately 10% over the same skew angle change. Thus the
segmenting of the air bearing members results both in a quicker
take off of the magnetic head from the magnetic surface and less
change in flying height as the skew angle changes. Changes in the
skew angle can result from the actuation of the rotary actuator as
described before.
It is thought that the fact that the cross sectional area of the
individual air bearing members changes only slightly as the skew
angle changes allow the lift forces to remain essentially the same
so as to maintain the head assembly at very near a constant flying
height. Even though in the embodiment shown in FIGS. 7 through 9,
the cross sectional configuration of the air bearing members is
changed from a circle to a square or a rectangle still with the
change in the skew angle the cross sectional area presented to the
air film remains substantially the same in contrast to the changes
in the air bearing member cross section facing the air film in the
prior embodiment shown in FIG. 2. As a result only a slight change
in flying height is realized by use of the invention while much
greater flying height changes are realized with the prior device
shown in FIG. 2.
* * * * *